From 85d825dbf4899a69407338bae462a59aa9a37326 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 14 Apr 2022 21:57:49 -0400
Subject: [PATCH] ext4: force overhead calculation if the s_overhead_cluster
 makes no sense
Git-commit: 85d825dbf4899a69407338bae462a59aa9a37326
Patch-mainline: v5.18-rc4
References: bsc#1200870

If the file system does not use bigalloc, calculating the overhead is
cheap, so force the recalculation of the overhead so we don't have to
trust the precalculated overhead in the superblock.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/ext4/super.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 23a9b2c086ed..d08820fdfdee 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5289,9 +5289,18 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	 * Get the # of file system overhead blocks from the
 	 * superblock if present.
 	 */
-	if (es->s_overhead_clusters)
-		sbi->s_overhead = le32_to_cpu(es->s_overhead_clusters);
-	else {
+	sbi->s_overhead = le32_to_cpu(es->s_overhead_clusters);
+	/* ignore the precalculated value if it is ridiculous */
+	if (sbi->s_overhead > ext4_blocks_count(es))
+		sbi->s_overhead = 0;
+	/*
+	 * If the bigalloc feature is not enabled recalculating the
+	 * overhead doesn't take long, so we might as well just redo
+	 * it to make sure we are using the correct value.
+	 */
+	if (!ext4_has_feature_bigalloc(sb))
+		sbi->s_overhead = 0;
+	if (sbi->s_overhead == 0) {
 		err = ext4_calculate_overhead(sb);
 		if (err)
 			goto failed_mount_wq;
-- 
2.35.3